(CNN) -- When Hurricane Irene hit, 11-year-old Zahir Robinson and his mother took shelter on a bed in the upstairs bedroom of their apartment in Newport News, Virginia.

Just after noon on Saturday, an "extremely large tree" toppled by the high winds smashed into the room and pinned the youth beneath it, according to local police.

Despite frantic efforts to remove the tree, including the use of a large crane to lift it, the boy died -- one of 15 fatalities in six states so far from the storm.

Eight of the deaths involved falling trees or limbs broken off in the hurricane. While the prospect of toppled trees and crashing limbs is easy to imagine, planning against such a threat is difficult.

In North Carolina, three of the six known deaths were tree-related, while the lone death reported in Maryland involved a tree falling on a house and all four deaths in Virginia -- including Robinson's -- were caused by overturned trees.

"I am saddened to learn of this unfortunate tragedy," Newport News Mayor McKinley Price said of Robinson's death. "My thoughts and prayers go out to the family of this young child. I urge our residents to take all precautions necessary to remain safe during and after this storm."

Falling trees or limbs snapped off in high winds pose a particularly difficult threat to avoid. The size and weight of a toppled tree, which can exceed 10,000 pounds, make it an unstoppable force, while the random nature of falling tree limbs pose an unpredictable danger.

When Hurricane Fran hit North Carolina in 1996, half the 24 deaths there involved falling trees or limbs, according to information posted online by the Renaissance Computing Institute at East Carolina University.

"Before hurricane season, assess your property to ensure that landscaping and trees do not become a wind hazard," the National Hurricane Center warns on its website. "Trim dead wood and weak / overhanging branches from all trees. Certain trees and bushes are vulnerable to high winds and any dead tree near a home is a hazard."